I've Been Having An Extra Eyelid For A While. But

I've been having an extra eyelid for a while. But usually this was whenever I was tired of hadn't slept well.

The problem is, that the past few months it's been constantly. Even when I've slept well. I believe it's called ''triple eyelid'' but I'm not sure. What can I do to treat it? Where should I go?

Thank you in advance.